As described by Kennedy et al in U.S. Pat. No. 8,110,115, water is essential to the oil and gas industry. In an oil or gas well, water is used to cool and lubricate the drillbit and to extract debris. Accordingly, drilling a well may require hundreds of thousands of gallons of water. Water is also recovered as a byproduct of oil and gas wells as produced water.
Furthermore, the process of hydraulic fracturing uses a large amount of water. Hydraulic fracturing, or racking (as it is commonly called and used herein), is a commonly used process to increase production and recovery in an oil or gas well. In hydraulic fracturing, fluid is injected at high pressure into a well to crack or fracture in the rock structures possessing hydrocarbons. The fracture width is usually maintained through the use of a proppant such as sand, ceramic, or other particulates. Maintaining the fracture width allows hydrocarbons to flow to the surface of the well. In additition to fracturing the rock, water also serves as a transport medium for the proppant. Accordingly, the hydraulic fracturing process requires millions of gallons of water per well. Often, a large percentage of the water used in hydraulic fracturing is recovered as flowback water.
Consequently, oil and gas companies must supply oil and gas wells with the requisite amount of water, and must manage the flowback and produced water recovered from the well. To accommodate the supply need, water is typically transported through temporary pipelines or trucked to the well site. However, water recovered from the well is unclean and filled with hydrocarbons, suspended solids, heavy metals, and bacteria. The recovered water must therefore be filtered and cleaned before it can be reused in the fracking process or introduced into the environment. For this reason, the recovered water is typically trucked from the well site to a filtering location, and then trucked from the filtering location to its next destination. The process of using trucks to transport the water increases the volume of traffic on roads and requires fossil fuels to power the trucks. Similarly, a company may construct a piping system to pump the water through the piping system to and from a filtering location, but such a piping system is a considerable expense. As an alternative to transporting the water by truck or constructing a piping system, a filtering company may set up a facility at the well site to filter the water, or bring in a large filtration system attached to a trailer to reuse the flowback water for the hydraulic fracturing process. However, this requires additional expense to set up a filtering facility. Furthermore, once the hydraulic fracture process is complete, the recovered water must be transported to another location.
In the prior art applicant is also aware of the following United States patents and published patent applications which attempt to provide mobile systems for water treatment:
U.S. Pat. No. 6,077,448 which issued Jun. 20, 2000, to Tran-Quok-Nam et al for An Oil/Grit Interceptor which discloses a multi-chambered tank providing partial separation of pollutants contained in effluent. With the exception of effluent flow via a bypass in the event of tank overloading, effluent drops into a first chamber and from the first chamber passes to a second chamber. Trash and debris is collected in the first chamber and free petroleum based products are separated and held in the second chamber. Effluent from the second chamber passes into a third chamber where sediment is separated.
U.S. Pat. No. 6,899,808 which issued May 31, 2005, to Ott for a System For Processing Polluted Water discloses using inline first, second and third containers where a pair of partitions separate the containers and where a corresponding pair of weirs are included in their respective partitions and are transversely offset from one another.
U.S. Pat. No. 7,578,930 which issued Aug. 25, 2009, to Williamson et al for A Mobile Water Treatment System discloses the use of separation and filtration components mounted on a trailer. The components are described as removing particulates and filtering contaminants from effluent water such as storm water, waste water, or drain water. The trailer based system is described as providing a mobile water treatment system which can be transported to a construction location or other storm water or waste water site on a temporary basis and used to treat the water by removing free and disbursed oils, capturing floatable debris, sediment and settleable solids.
U.S. Pat. No. 8,110,115 which issued Feb. 7, 2012, to Kennedy et al for A Mobile Water Treatment discloses transporting dirty fluid in a storage container on a motor vehicle between first and second locations wherein at the second location the fluid is filtered by a filtration system and discharged. A pump is configured to on-load fluid into the storage container and is also adapted to offload the fluid from the storage container once the fluid has been filtered.
United States published patent application, publication no. 2007/0246414, published on Oct. 25, 2007 in the application of Page et al for A Water Treatment And Apparatus Method describes the use of compartments for holding waste water and separator/recovery mechanisms, evaporation compartments, a condensation recovery system and a clean water holding compartment. In one disclosed embodiment, a platform such as a skid supports a phase separation tank, an evaporation tank with condenser, and a clean water recovery tank. Fluid transfer mechanisms interconnect the tanks. The phase separation tank may provide three phase separation into solids, water and oil fraction. The fluid transfer between the separation and evaporation tanks may pass through a transitional tank such as a floc tank.
United States patent application, publication no. 2008/0061003, published Mar. 13, 2008, in the application of Mueller for An Apparatus For Recycling Of Oil Based Drilling Fluid Contaminated With Water And Water Contaminated With Oil Based Drilling Fluid describes using an emulsion breaking tank, a water treatment tank, a filter press, and hydrocarbon filters. Mueller describes that there is a need for a skid-mounted apparatus to effectively break emulsions on an off shore rig thereby reducing the need to transport slop water on shore. Mueller describes, in one embodiment, the use of two modules wherein one module separates the bulk part of the water fraction from oil based/synthetic based drilling mud, from where the extracted water is pumped to the second module where it is treated with a flocculent to eliminate/minimize hydrocarbon, organic and heavy metal contamination. The treatment sludge containing the contaminant loaded flocculent is directed to a filter press for dewatering and solidification for transport and disposal. The cleaned water phase is then pumped over a further filter and discharged.
United States patent application, publication no. 2009/0178978, published Jul. 16, 2009, in the application of Beebe et al for Drilling Fluid Treatment Systems describes the use of at least one holding tank mounted on a base for holding well fluid to be treated, a centrifuge for centrifuging a mixture of well fluid and solids from the at least one holding tank to produce reusable fluid, and a mixing tank for mixing an aqueous solution for introduction to the well fluid held in the at least one holding tank. The aqueous solution includes flocculent and coagulant.
Beebe et al describe that U.S. Pat. No. 4,536,286 discloses a transportable waste treatment which is completely mobile and capable of treating high mud volumes. This system is self-contained having chemical storage, chemical pumps, sludge pumps, water pumps, laboratory, centrifuge, conveyors, etc., and has weight, height and width suitable for highway travel. A skid incorporates three settling tanks and two chemical tanks for flocculation. Waste liquids containing solids enter a first settling tank and are mixed with flocculation chemicals. Solids settle to the tapered bottom of the tank for collection by a suction located at the apex of the tank bottom. Partially clarified liquid from the first settling tank overflows a weir to the next adjacent settling tank and similarly for the second to the third settling tank.